混杂增强(CNTs+TiB2)/Cu复合材料制备与性能

本文以碳纳米管（CNTs）和TiB2颗粒作为增强相,首先利用球磨、表面吸附和热压烧结相结合技术制备具有层叠结构的CNTs/Cu复合材料,改善了CNTs在铜基复合材料中易团聚问题。CNTs/Cu复合材料的致密度和导电率随CNTs含量增加而降低,抗拉强度和伸长率随CNTs含量增加先升高后降低,当含量为0.1 wt.%时综合性能最优,致密度、导电率和抗拉强度分别为97.57%、91.2 %IACS和252 MPa。而球磨后热压烧结的1 wt.% TiB2/Cu复合材料致密度、导电率和抗拉强度分别为97.61%、58.3 %IACS和436 MPa。在此基础上,将TiB2颗粒原位引入到具有层叠结构的CNTs/Cu复合材料,制备获得混杂增强(CNTs+TiB2)/Cu复合材料。相比单一CNTs（或TiB2）增强铜基复合材料,(CNTs+TiB2)/Cu复合材料的强度提升显著。其中,(0.1 wt.% CNTs+1 wt.% TiB2)/Cu复合材料的导电率和抗拉强度分别为56.4 %IACS和531 MPa,相比1 wt.% TiB2/Cu,其导电率仅降低3.3%,而抗拉强度则升高21.8%。这主要归因于片层间CNTs可起承担和传递载荷作用,同时片层间弥散分布的TiB2颗粒可以钉扎位错,两种强化机制共同作用使(CNTs+TiB2)/Cu复合材料的抗拉强度显著提升。     

Nanostructured bulk glassy Cu_(60)Zr_(30)Ti_(10) alloy with high strength and good ductility in cast state

1　INTRODUCTIONSinceaseriesofmetallicbulkglassyalloyswithexpectedmechanicalpropertiesandhighglassformingabilityhavebeenfound[13] ,particularattemptshavebeendonetoimprovethemechanicalpropertiesoftheglassyalloystomeetengineeringapplications .Bycrystallizingthemetallicglasses ,nanostructuredal loyscontainingnanocrystallinephasesandglassyma trixwereobtainedandthemechanicalpropertiesofthealloyswereenhancedbyhomogeneousdispersionofnanoscalemetallic particlesintheAl [4 ,5] ,Fe Ni [6 ] andMg [7]…     

电流对碳纳米管增强铜基复合材料载流摩擦学性能的影响

采用粉末冶金方法在相同的工艺条件下制备纯铜和碳纳米管含量为10%（体积分数）的铜基复合材料。在一种销盘式载流摩擦磨损试验机上考察了不同电流条件下2种材料的载流摩擦磨损性能。结果表明：纯铜和铜基复合材料的摩擦系数和磨损率均随电流的增大而增大,但是电流对纯铜材料的影响更加显著;纯铜材料的主导磨损机制是电弧烧蚀磨损,而铜基复合材料的主导磨损机制是塑性流动变形;碳纳米管可以改善铜基复合材料的载流摩擦磨损性能。     

Effect of Ball Milling on the Defeat of Few-Layer Graphene and Properties of Copper Matrix Composites

Graphene-reinforced copper composites recently have attracted more attention, since they exhibited excellent mechanical properties and could be used widely in many fields. Few-layer graphene （FLG） and copper powder were mixed by ball milling to produce homogeneous composite powders. Then, FLG-reinforced copper composites （FLG/Cu） were fabricated by spark plasma sintering （SPS） using the composite powders with a FLG volume fraction of 2.4 vol%. The effects of the rotating speed and the time of ball milling were analyzed based on the microstructure evolution and properties of the FLG/Cu composites. Obvious strengthening effect of FLG was found for the composites, and the conductance of the composite reaches 70.4% of IACS. The yield strength of the composite produced by ball milling at a speed of 100 r/rain for 4 h is 376 MPa, which is 2.5 times higher than that of copper and higher than that of copper composite enhanced by 5 vol% CNTs （360 MPa）. The defects produced in FLG with the increase of rotating speed and time could reduce the mechanical and conductive properties of the composites.     

Microstructure and Mechanical Properties of Mg–7.4% Al Alloy Matrix Composites Reinforced by Nanocrystalline Al–Ca Intermetallic Particles

Mg–7.6% Al(in mass fraction) alloy matrix composites reinforced with different volume fractions of nanocrystalline Al3Ca8 particles were synthesized by powder metallurgy,and the effect of the volume fraction of reinforcement on the mechanical properties was studied.Room temperature compression test reveals considerable improvement on mechanical properties as compared to unreinforced matrix.The compressive strength increases from 683 MPa for unreinforced alloy matrix to about 767 and 823 MPa for the samples having 20 and 40 vol% of reinforcement,respectively,while retaining appreciable plastic deformation ranging between 12 and 24%.The specific strength of the composites increased significantly,demonstrating the effectiveness of the low-density Al3Ca8 reinforcement.     

In Situ TiC/FeCrNiCu High-Entropy Alloy Matrix Composites: Reaction Mechanism,Microstructure and Mechanical Properties

In situ TiC particles-reinforced FeCrNiCu high-entropy alloy matrix composites were prepared by vacuum induction melting method.The reaction mechanisms of the mixed powder(Ti,Cu and C) were analyzed,and the mechanical properties of resultant composites were determined.Cu_4Tiwere formed in the reaction of Cu and Ti when the temperature rose to 1160 K.With the temperature further increased to 1182 K,newly formed Cu_4Tireacted with C to give rise to TiC particles as reinforcement agents.The apparent activation energy for these two reactions was calculated to be 578.7 kJ/mol and 1443.2 kJ/mol,respectively.The hardness,tensile yield strength and ultimate tensile strength of the 15 vol% TiC/FeCrNiCu composite are 797.3 HV,605.1 MPa and 769.2 MPa,respectively,representing an increase by 126.9%,65.9% and 36.0% as compared to the FeCrNiCu high-entropy base alloy at room temperature.However,the elongation-to-failure is reduced from 21.5 to 6.1 %with the formation of TiC particles.It was revealed that Orowan mechanism,dislocation strengthening and load-bearing effect are key factors responsible for a marked increase in the hardness and strength of the high-entropy alloy matrix composites.     

高能球磨结合粉末冶金法制备碳纳米管增强7055Al复合材料的微观组织和力学性能

采用高能球磨结合粉末冶金工艺制备了碳纳米管(CNT)含量(体积分数)分别为0、1%和3%的CNT/7055Al复合材料。采用OM、SEM、TEM以及拉伸实验等方法研究了CNT/7055Al复合材料的CNT分布、晶粒结构、近界面结构及力学性能,分析了复合材料的强化机制和各向异性。结果表明,CNT/7055Al复合材料为无CNT的粗晶区与富集CNT的超细晶区组成的双模态晶粒结构;CNT在Al基体的超细晶区中分散良好,CNT-Al界面干净清洁,界面反应产物少;3%CNT/7055Al复合材料沿挤压方向的抗拉强度达到816 MPa,但延伸率仅为0.5%。细晶强化和Orowan强化是CNT/7055Al复合材料主要的强化机制。由于CNT沿不同方向的增强效率不同以及粗晶条带组织的存在,复合材料表现出比基体合金更强烈的各向异性,在垂直挤压方向的拉伸性能要弱于沿挤压方向的拉伸性能。     

CNTs/AZ91D镁基纳米复合材料的热处理及其力学性能

采用高能超声分散技术和金属型重力铸造工艺制备了CNTs/AZ91D镁基纳米复合材料,并对复合材料进行了固溶T4热处理和固溶时效T6热处理。T4态1.0CNTs/AZ91D复合材料的抗拉强度、伸长率分别为285 MPa、17.3%,与铸态复合材料的抗拉强度(196MPa)和伸长率(4.1%)相比,分别提高了45%、322%。T6态的抗拉强度进一步提高到296MPa,特别是屈服强度显著提高到155MPa,伸长率有所降低,但仍有5.5%。利用OM、SEM、TEM观察1.0CNTs/AZ91D复合材料的显微组织。结果表明,碳纳米管具有细化晶粒、促进滑移和孪生、载荷转移等作用,从而能够明显提高CNTs/AZ91D复合材料的综合力学性能。     

C/CF/Cu复合材料界面和抗拉强度研究

采用树脂碳化方法制备了碳/碳纤维(C/CF)先驱丝,用压力浸渗凝固成型方法制备了碳/碳纤维/铜(C/CF/Cu)复合材料,借助抗拉强度测试及扫描电镜下复合材料界面和相组成物分布观察,探讨了C、CF和Cu三组元复合界面特性以及碳纤维丝类型和C/CF先驱丝体积分数对C/CF/Cu复合材料抗拉强度的影响.结果表明,C/CF/Cu复合材料的微观界面是碳纤维单丝-树脂碳化碳-铜双复合界面,此界面属于无化学反应的弱复合界面,铜对C/CF先驱丝的机械锁紧力是提高界面强度和复合材料强度的关键因素.当凝固成型压力为28.5MPa时,1k碳纤维丝的C/CF先驱丝体积分数为25%和3k碳纤维丝的C/CF先驱丝体积分数为44.7%的复合材料的抗拉强度达到较高值,分别为595MPa和587MPa,均为纯铜抗拉强度的3倍以上.3k丝制成的一次C/CF先驱丝内碳纤维丝的数量较多,影响复合材料的界面强度,而选用1k碳纤维丝比较有利.     

Cu含量对重力铸造Al-Cu-Mg-Sc合金组织及力学性能的影响

在重力铸造条件下制备了不同Cu含量(4%~6%,质量分数,下同)Al-Cu-Mg-Sc合金,采用500 ℃×4 h＋520 ℃×6 h的双级固溶,水冷后进行175 ℃×5 h时效。通过维氏硬度测试、室温拉伸性能测试试验、扫描电镜分析(SEM)等手段,研究了不同Cu含量对试验合金显微组织和力学性能的影响,进而优化Al-Cu-Mg-Sc铝合金成分。结果表明,经热处理后,随Cu含量从4.26%提高至5.58%,Al₂Cu析出相含量持续提高,热处理后合金屈服强度从191 MPa提升至216 MPa,抗拉强度从323 MPa提升至355 MPa,伸长率维持在13%附近。然而,当Cu含量较高时(6.13%),微观组织中Al₂Cu相体积分数较高,固溶后进入基体的Al₂Cu相数目有限,有大量Al₂Cu相残留在晶界处,经过时效处理后,合金的强化效果不能随Cu含量的增加而继续提升。因此整体上,随Cu含量提高,时效态高Cu含量合金的硬度和抗拉强度先增加随后趋于平稳,断后伸长率呈现先增加后降低的规律。Cu含量为5.58%的铸造Al-Cu-Mg-Sc铝合金时效后获得最佳综合性能,其硬度为117 HV,抗拉强度和屈服强度分别为355 MPa、216 MPa,断后伸长率为13.5%。     

高能球磨法制备的碳纳米管增强铝基复合材料的微观组织和力学性能

采用高能球磨法制备了不同体积分数的碳纳米管(CNT)与Al粉的混合粉末,用粉末冶金工艺制备了CNT/A1复合材料.微观结构分析表明.球磨可以分散一定含量的CNT到Al基体中,并与其产生良好结合.在适当的球磨工艺下.球磨不会造成CNT的严重损伤.拉伸实验表明,CNT体积分数为1.5%时,力学性能达到了最高值,屈服强度相对于纯A1基体提高了53.6%.而CNT体积分数为3%时,形成了大量的CNT团聚,力学性能迅速下降.CNT/A1复合材料的主要强化机制为细晶强化和载荷传递.     

Cu和Sb元素添加对Sn-Bi共晶合金性能的影响

向Sn-Bi共晶合金中同时添加Cu和Sb元素设计额定温度为142℃的易熔合金,并对合金的熔点、相组成、准静态拉伸性能、焊接接头力学性能进行了研究.结果表明,Cu与Sb元素的添加使合金的熔点上升,但是合金的过冷度和熔化潜热下降.添加Cu和Sb元素后,在合金基体内形成了块状的SnSb相和长条状的Cu6Sn5、Cu3Sn相,...     

Developing high performance squeeze cast Al-Cu alloys with high Fe and Cu contents

In this paper, the microstructural evolution and mechanical properties of squeeze cast Al-Cu alloys with different amounts of Cu and Fe after T7 heat treatment were investigated using various methods, including optical microstructure (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron probe micro-analyzer (EPMA), and tensile testing. Results show that better comprehensive mechanical properties of squeeze cast Al-Cu alloys can be achieved by designing the Fe and Cu contents. These results can be attibuted to an increase in precipitate particles in the α(Al) matrix and the formation of nano-sized iron-rich intermetallics (IRIs). Ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) of the Al-6.5Cu-0.6Mn-1.0Fe alloy were as high as 314 MPa, 293 MPa, and 6 %, respectively. These values were close to those of Al-Si alloys with high Fe content (1.0 %) under applied pressure, and this indicates the high potential for developing recycled squeeze cast Al-Cu cast alloys.     

Development of ultrafine grained high strength Al–Cu alloy by cryorolling

In the present paper, the microstructure and mechanical properties of a precipitation hardening Al–Cu (2219) alloy subjected to cryorolling, low temperature annealing and ageing treatments are reported. Under optimal processing conditions, ultrafine grained microstructure with improved tensile strength (540 MPa) and good ductility (11% tensile elongation) was obtained.     

Effect of Spark-Plasma-Sintering Conditions on Tensile Properties of Aluminum Matrix Composites Reinforced with Multiwalled Carbon Nanotubes (MWCNTs)

In this study, aluminum (Al) matrix composites containing 2 wt.% multiwalled carbon nanotubes (CNTs) were fabricated by powder metallurgy using high-energy ball milling (HEBM), spark plasma sintering (SPS), and subsequent hot extrusion. The effect of SPS conditions on the tensile properties of CNT/Al composites was investigated. The results showed that composites with well-dispersed CNTs and nearly full-density CNT/Al can be obtained. During HEBM, CNTs were shortened, inserted into welded Al powder particles, bonded to Al, and still stable without CNT-Al reaction. After consolidation, Al₄C₃ phases formed in composites under different sintering conditions. With the increase of sintering temperature and holding time, the strength decreased. Conversely, the ductility and toughness noticeably increased. As a result, a good balance between strength (367 MPa in ultimate tensile strength) and ductility (13% in elongation) was achieved in the as-extruded CNT/Al composite sintered at 630°C with a holding time of 300 min.     

Advances in deformation processed gold composites

Conventional metallic composites are comprised of a metal matrix with a ceramic second phase. In recent years, composites have been developed in which both the matrix and the reinforcing phase are ductile metals. In 1998 a 90 vol%Au – 10 vol% Ag metal-metal composite wire was produced and found to possess both high tensile strength (550 MPa) and low electrical resistivity (2.56 m ohm-cm). In that composite, the silver reinforcing phase consisted of sub-micron diameter filaments parallel to the wire axis. This article describes the microstructures, mechanical properties, and electrical resistivity of three gold matrix composites in which the reinforcing phases are 7 vol% Ag, 14 vol% Ag, and 7 vol%Pt. These composites were drawn to diameters as small as 60 microns. Results from wedge bonding trials with these composite wires are also reported.     

利用搅拌铸造结合超声处理法制备镁基复合材料

在目前的研究中,利用搅拌铸造结合超声处理方法成功地制备出了不同体积分数(5vol%和10vol%)的微米颗粒增强的AZ31B镁基复合材料。利用350℃,12:1的挤压比对铸锭进行了挤压处理。利用金相和扫描电子显微镜对复合材料的微观结构进行了研究。复合材料的微观结构显示,增强体具有相对均匀的分布且晶粒获得了显著的细化。微米碳化硅颗粒的存在可以显著的提高基体合金的显微硬度﹑弹性模量以及抗拉伸强度。此外,复合材料的显微硬度﹑弹性模量以及抗拉伸强度随着微米颗粒含量的增加而增加。     

Ti2SnC颗粒增强铜基复合材料的力学性能

用粉末冶金方法制备了一种以三元层状陶瓷Ti2SnC为增强相的Cu/Ti2SnC复合材料，研究了增强相的含量对复合材料的显微结构和硬度、拉伸强度等力学性能的影响。结果表明，Ti2SnC对于铜是一种有效的增强相，当Ti2SnC的体积含量为20％（体积分数，下同）时增强效果最佳，屈服强度和拉伸强度分别达到319MPa和440MPa，是相同工艺条件下制备的纯铜的屈服强度和拉伸强度的4倍和2倍，并保持12％的延伸率。强化是由于铜基体晶粒的细化和位错塞积引起的。     

碳纤维-FeCoCrNiAl高熵合金颗粒混杂增强7075铝基复合材料的力学性能及断裂行为

为探究双相增强体对铝基复合材料拉伸性能和断裂行为的影响,采用真空热压烧结工艺在580 ℃,30 MPa条件下保温10 min制备了FeCoCrNiAl高熵合金颗粒增强7075铝基复合材料（HEA_p/Al）,Ni-Co-P镀层修饰碳纤维增强7075铝基复合材料（CF/Al）和FeCoCrNiAl高熵合金颗粒及Ni-Co-P镀层修饰碳纤维混杂增强铝基复合材料（CF-HEA_p/Al）。并对不同复合材料微观结构及拉伸性能进行分析表征及比较。结果表明：CF-HEA_p/Al复合材料的屈服强度（YS）与极限拉伸强度（UTS）随纤维含量的升高（体积分数由0至40%）呈现先增大后降低的变化,延伸率则逐渐降低。鉴于Ni-Co-P镀层修饰碳纤维与FeCoNiCrAl高熵合金颗粒的混杂强化效应, CF-HEA_p/Al复合材料的YS和UTS较HEA_p/Al与CF/Al复合材料明显提高,且其断口表现出基体韧性断裂及纤维拔出与断裂的多种失效特征。     

Microstructure and Fracture Behavior of Zr55Cu30Al10Ni5 Bulk Metallic Glass and Its Composites Containing ZrO2

The microstructure and fracture behavior of Zr55Cu30Al10Ni5 monolithic glass and Zr55Cu30Al10Ni5 reinforced with 5%-7% ZrO2 particles composites have been studied. Vein-like pattern is the main fracture morphology of the matrix, while the smooth regions can be observed on the composites fracture surface besides vein-like pattern. The fracture strength increases from 1716 MPa to 2138 MPa after adding 7vol% ZrO2 particles with average particle size of 1 μm into the matrix, but the composites show no visible plasticity due to formation of Cu10Zr7 and CuZr phases in the matrix